The subject matter described herein generally relates to power saving techniques via server consolidation. It is largely agreed that infrastructure and energy (I&E) costs are the largest contributor to the cost of operating a data center and are generally much larger than IT costs. Therefore, reducing the cost of I&E is a major initiative of most data centers. One promising approach for reducing the I&E costs, prompted by virtualization and hardware-assisted isolation, is server consolidation.
Server consolidation is based on the observation that many enterprise servers do not maximally utilize the available server resources all of the time. Co-locating applications, perhaps in individual virtual machines, thus allows for a reduction in the total number of physical servers, minimizes server sprawl as well as the total data center space requirements.
Consolidation reduces the total power consumed by the applications because existing servers are not energy proportional; that is, a significant amount of power is consumed even at low levels of utilization. Though server features like voltage and frequency scaling modify this curve, there is still substantial power drawn at idle or low utilization. Consolidation thus provides an opportunity to reduce the overall power consumed by operating the servers in a range with a more attractive performance/Watt. However, effective consolidation is difficult.